CD34⁺ progenitors transduced with nef, mutated in a region important for dimerization, still show a strongly impaired T-cell development in FTOC. The figure shows mean values of thymocyte generation ratio and their standard deviations calculated from the data generated in at least 3 independent experiments. An asterisk (*) over a bar indicates a statistically significant difference between the experimental construct and control data sets (P < .05).